1. Field of the Invention
The present invention relates to an electric system protection apparatus, and more particularly, to an over-current protection apparatus.
2. Discussion of Related Art
In general, a switching mode power supply employing pulse width modulation (PWM) is a device that transforms an input direct current (DC) voltage into a voltage having a square wave shape using a semiconductor device, e.g., a power metal-oxide-semiconductor field effect transistor (MOSFET), as a switch, and then obtains a controlled DC output voltage using a filter. The switching mode power supply controls the flow of current by using a switching processor of the semiconductor device, and is thus a high-efficient, high-durable, compact, and light device compared to a conventional linear type power supply.
When over-current is sensed, the switching mode power supply may perform any of various control methods, e.g., control current not to continuously increase at an output side thereof, reduce an amount of current supplied, or increase the amount of current supplied.
However, in the case of a switching mode power supply employing a constant-current supply method, a current-mode method, a voltage-mode method, a sequential oscillation method, or the like, even if over-current is sensed, output current continuously flows when the over-current is continuously maintained.
When the over-current continuously flows, unnecessary power may be supplied, or a switching device or other components may be maintained to be heated and thus be damaged. Thus, fire may occur, a circuit or equipment may be damaged, and a system may be difficult to operate normally.